Buoyancy driven mass transfer in a liquid desiccant storage tank

Josh A. Quinnell, Jane H. Davidson

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

A new concept for long-term solar thermal storage is based on the absorption properties of aqueous calcium chloride. Water, diluted and concentrated calcium chloride solutions are stored in a single tank. An immersed heat exchanger and stratification manifold are used to preserve long-term sorption storage, and to achieve thermal stratification. The feasibility of sensible heating the tank via large-scale natural convection without mixing salt solutions is demonstrated via measurements of velocity, CaCl2 mass fraction, and temperature in a 1500 l prototype tank. Experiments are conducted over a practical range of the relevant dimensionless parameters. For Rayleigh numbers from 3.4 × 108 to 5.6 × 1010 and buoyancy ratios from 0.8 to 46.2, measured Sherwood numbers are 11 ± 2 to 62 ± 9, and the tank is thermally stratified. Convective mixing between salt layers is inhibited by the presence of a steep density gradient at the interface between regions of differing mass fraction. The predicted storage time scales based on mixing via natural convection for the reported Sherwood numbers are 160-902 days.

Original languageEnglish (US)
Article number041009
JournalJournal of Solar Energy Engineering, Transactions of the ASME
Volume135
Issue number4
DOIs
StatePublished - Nov 27 2013

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